Paul Watson, the founder of the anti-whaling group Sea Shepherd, has been arrested in Germany and will be extradited to Costa Rica.

"I am currently being held in Frankfurt on charges from Costa Rica," Watson has tweeted.

"Court appearance in the morning."

Sea Shepherd has labelled the arrest as "nonsense" and called for the charges against the Canadian-born Watson to be dropped.

The activist group says Watson, who is the captain of the Steve Irwin ship, has been arrested on a Costa Rican warrant over an incident which occurred in 2002.

"The specific 'violation of ships traffic' incident took place on the high seas in Guatemalan waters, when Sea Shepherd encountered an illegal shark finning operation, run by a Costa Rican ship called the Varadero," the group said in a statement.

"On order of the Guatemalan authorities, Sea Shepherd instructed the crew of the Varadero to cease their illegal shark finning activities and head back to port to be prosecuted."

Sea Shepherd claims that while it was taking the Varadero back to port, the tables were turned.

"A Guatemalan gunboat was dispatched to intercept the Sea Shepherd crew," the group said.

"The crew of the Varadero accused Sea Shepherd of trying to kill them, while the video evidence proves this to be a fallacy.

"To avoid the Guatemalan gunboat, Sea Shepherd then set sail for Costa Rica, where they uncovered even more illegal shark finning activities in the form of dried shark fins by the thousands on the roofs of industrial buildings."

Sea Shepherd says Watson is being assisted while in prison by members of the European Parliament Daniel Cohn-Bendit and Jose Bove.

"Our hope is that these two honourable gentlemen can set Captain Watson free before this nonsense goes any further," the group said.

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